On Valentine's Day, the young couple posted a photo of the two together, highlighting her baby bump. "I love you so very much, honey! Thank you for making today special," Joy wrote in the caption.

It was pretty innocent, but the photo gave fans a forum to argue about when the 20-year-old Joy-Anna first had sex with her 24-year-old husband, notes InTouch Weekly. The Duggar family's religious views do not permit premarital sex.

Many fans were doing the math, and some defended her, insisting that she did not have sex before the wedding in May 2017.

"Her due date is in February 22, 2017 her conception date was on June 1st, 2017 and her wedding was on May 27, 2017. If anyone have doubt just check on Google reverse conception date," one user wrote.

Another fan thinks their baby was conceived on wedding night. "This would have happened most likely wedding night. May 26th. Like i said during the first week," the fan wrote.

One fan had an incredibly detailed reason for why she thinks the baby will be a boy. "Wedding night babies are usually boys. Y [chromosome sperm] swim faster so if you’re fertile and get pregnant on the first go probably a boy," the fan wrote.

Others argued about the possibility of Joy-Anna carrying twins.

"It's not twins," one fan wrote. "They rarely make it to full term. She's a few days out. Some women just have bigger [bellies] than others. Also [it's] not [a] secret that these ladies have big babies, look at the sizes of Jill and Jessa's when they had them." (It is true that some twins are born before 37 weeks of pregnancy.)

Fans of the Duggar family, which is now featured on TLC's Counting On, have long speculated that Joy-Anna and Forsyth had sex before they married.

In January, Joy-Anna made a comment that made some fans think the baby was conceived in March 2017. Joy-Anna and Forsyth also moved up their wedding from October 2017 to May 2017 without explanation. Some fans also thought Joy-Anna already gave birth to her child last month.